linux-kernel - [PATCH v2 07/14] arm64: Make the PHYS_MASK

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Date: Fri, 12 Apr 2024 09:42:06 +0100
From: Steven Price <steven.price@....com>
To: kvm@...r.kernel.org,
	kvmarm@...ts.linux.dev
Cc: Steven Price <steven.price@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Marc Zyngier <maz@...nel.org>,
	Will Deacon <will@...nel.org>,
	James Morse <james.morse@....com>,
	Oliver Upton <oliver.upton@...ux.dev>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Zenghui Yu <yuzenghui@...wei.com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Joey Gouly <joey.gouly@....com>,
	Alexandru Elisei <alexandru.elisei@....com>,
	Christoffer Dall <christoffer.dall@....com>,
	Fuad Tabba <tabba@...gle.com>,
	linux-coco@...ts.linux.dev,
	Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>
Subject: [PATCH v2 07/14] arm64: Make the PHYS_MASK_SHIFT dynamic

Make the PHYS_MASK_SHIFT dynamic for Realms. This is only is required
for masking the PFN from a pte entry. Elsewhere, we could still use the
PA bits configured by the kernel. So, this patch:

 -> renames PHYS_MASK_SHIFT -> MAX_PHYS_SHIFT as supported by the kernel
 -> Makes PHYS_MASK_SHIFT -> Dynamic value of the (I)PA bit width
 -> For a realm: reduces phys_mask_shift if the RMM reports a smaller
    configured size for the guest.

Co-developed-by: Suzuki K Poulose <suzuki.poulose@....com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
Signed-off-by: Steven Price <steven.price@....com>
---
 arch/arm64/include/asm/kvm_arm.h       | 2 +-
 arch/arm64/include/asm/pgtable-hwdef.h | 4 ++--
 arch/arm64/include/asm/pgtable.h       | 5 +++++
 arch/arm64/kernel/rsi.c                | 5 +++++
 4 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index e01bb5ca13b7..9944aca348bd 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -398,7 +398,7 @@
  * bits in PAR are res0.
  */
 #define PAR_TO_HPFAR(par)		\
-	(((par) & GENMASK_ULL(52 - 1, 12)) >> 8)
+	(((par) & GENMASK_ULL(MAX_PHYS_MASK_SHIFT - 1, 12)) >> 8)
 
 #define ECN(x) { ESR_ELx_EC_##x, #x }
 
diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
index ef207a0d4f0d..90dc292bed5f 100644
--- a/arch/arm64/include/asm/pgtable-hwdef.h
+++ b/arch/arm64/include/asm/pgtable-hwdef.h
@@ -206,8 +206,8 @@
 /*
  * Highest possible physical address supported.
  */
-#define PHYS_MASK_SHIFT		(CONFIG_ARM64_PA_BITS)
-#define PHYS_MASK		((UL(1) << PHYS_MASK_SHIFT) - 1)
+#define MAX_PHYS_MASK_SHIFT	(CONFIG_ARM64_PA_BITS)
+#define MAX_PHYS_MASK		((UL(1) << PHYS_MASK_SHIFT) - 1)
 
 #define TTBR_CNP_BIT		(UL(1) << 0)
 
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index afdd56d26ad7..f5376bd567a1 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -39,6 +39,11 @@
 #include <linux/sched.h>
 #include <linux/page_table_check.h>
 
+extern unsigned int phys_mask_shift;
+
+#define PHYS_MASK_SHIFT		(phys_mask_shift)
+#define PHYS_MASK		((1UL << PHYS_MASK_SHIFT) - 1)
+
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 #define __HAVE_ARCH_FLUSH_PMD_TLB_RANGE
 
diff --git a/arch/arm64/kernel/rsi.c b/arch/arm64/kernel/rsi.c
index b93252ed6fc5..159bc428c77b 100644
--- a/arch/arm64/kernel/rsi.c
+++ b/arch/arm64/kernel/rsi.c
@@ -12,6 +12,8 @@ struct realm_config __attribute((aligned(PAGE_SIZE))) config;
 unsigned long prot_ns_shared;
 EXPORT_SYMBOL(prot_ns_shared);
 
+unsigned int phys_mask_shift = CONFIG_ARM64_PA_BITS;
+
 DEFINE_STATIC_KEY_FALSE_RO(rsi_present);
 EXPORT_SYMBOL(rsi_present);
 
@@ -62,5 +64,8 @@ void __init arm64_rsi_init(void)
 		return;
 	prot_ns_shared = BIT(config.ipa_bits - 1);
 
+	if (config.ipa_bits - 1 < phys_mask_shift)
+		phys_mask_shift = config.ipa_bits - 1;
+
 	static_branch_enable(&rsi_present);
 }
-- 
2.34.1